#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h> 
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#define TEST_DEVICE_FILENAME "/dev/test_dev" /* 设备文件名*/
#define BUFF_SZ 1024
int main() {
    int fd, nwrite, nread;
    char buff[BUFF_SZ];
    fd = open(TEST_DEVICE_FILENAME, O_RDWR);
    if (fd < 0)
    {
        perror("open");
        exit(1);
    }
    do {
        printf("Input some words to kernel(enter 'quit' to exit):");
        memset(buff, 0, BUFF_SZ);
        if (fgets(buff, BUFF_SZ, stdin) == NULL)
        {
            perror("fgets");
            break; }
        buff[strlen(buff) - 1] = '\0';
        if (write(fd, buff, strlen(buff)) < 0) /* 向设备写入数据 */ {
            perror("write");
            break; }
        if (read(fd, buff, BUFF_SZ) < 0) {
            perror("read");
            break; }
        else {
            printf("The read string is from kernel:%s\n", buff);
        }
    } while(strncmp(buff, "quit", 4));
    close(fd);
    exit(0);
}
